In redundant arrays of inexpensive disks (RAID) system, a device called a service controller (SVC) that monitors the state of a RAID apparatus and performs control according to the state is provided therein.
The SVC includes a micro-processing unit (MPU) that controls the SVC and a field programmable gate array (FPGA) that supports control performed by the SVC. The SVCs are used in a redundant form. When an FPGA of an SVC of one system detects a defect in an SVC of the other system, the SVC which has detected the defect transmits a signal (which will be hereinafter referred to as an “initialization signal”) that prompts initialization to the SVC whose defect has been detected. In this case, the FPGA of the SVC which has detected the defect transmits a high-level signal as the initialization signal using a predetermined signal line, and transmits a low-level signal as the initialization signal using another signal line. In the SVC whose defect has been detected, the FPGA which has received the initialization signal initializes its own SVC and notifies the MPU that the FPGA has received the initialization signal by an interrupt. Then, the MPU which has received the interrupt performs interrupt processing and does not perform control of the RAID apparatus until initialization is performed. Note that, when the SVC of the one system does not detect any defect in the SVC of the other system, the SVC of the one system transmits a low level signal as a signal of a normal state using the one signal line which is used for transmitting the initialization signal, and transmits a high level signal as a signal of a normal state using the other signal line.
Japanese Laid-open Patent Publication No. 2001-5743 and Japanese Laid-open Patent Publication No. 11-143783 are examples of the related art.